Hi to all,
Hi Videotechie,
What you call "Z axis" is actually the analogue video modulation applied to the oscilloscope or X/Y display's Cathode or Grid to produce a picture.
In a standard 1 Volt peak-to-peak video signal, the brightness intensity (Black to White) is the 0.7V (700 mV) analogue signal contained between the blanking level (0.3V) and peak White (1V). The complete signal with Sync is 1V Peak to Peak.
Labguys World web site shows two projects he built to use a X/Y display as a 525 line/60 Hz TV monitor (standard System M/NTSC scan rates). Both circuits use the LM1881 as a Sync separator and give good insight into what is necessary to achieve the desired goal.
Schematics, photos & extensive explanations in both projects.
1st project :
http://www.labguysworld.com/Project_Tiny_TV.htm
2nd project :
http://www.labguysworld.com/Project_Tiny_TV_2.htm
Best Regards
jhalphen
Paris/France